Duster 340 not a muscle car...

Bill Dedman is the only one that is correct.
..by definition,a musclecar was an intermediate with a large engine
Pony cars were small sports coupes like camaro and mustang and challenger
the nova maverick duster size models were actually economy cars that
the manufacturers' eventually stuffed more powerful engines in during those sales competitive years

So...by that "logic", a 421 Super Duty Catalina, a 409/409 Impala SS, a 427 Galaxie, or even a 390HP Chrysler 300 Letter Series aren't muscle cars? SERIOUSLY?!?!?!?!